Root Causes for Early Breakage of High-Voltage Fuse Links
1. Abnormally High Resistance
When exposed to sustained high temperatures, the metallic material of high-voltage fuse links undergoes electromigration, creating local voids and material erosion that directly push up internal resistance.
Extreme heat can melt solder joints, loosening the bonding between fuse links and electrodes and adding extra resistance to the whole assembly. Solder or flux vaporized by high heat may adhere to partial areas of the fuse link, forming tiny flaws that raise local resistance. Metal vaporization of the fuse conductor is another contributor to resistance growth. Where silver serves as the fuse material, silver ion migration will further increase overall resistance values.
2. Fuse Link Rupture
A high-voltage fuse is considered defective once it can no longer deliver its designed protection function. Fuse link aging frequently leads to rupture at rated current or even under lighter loads, so fuse breakage is categorized as a common failure mode in this paper.
There are three types of fuse rupture for high-voltage products: standard protective rupture triggered by circuit faults, unexpected rupture caused by component aging, and premature breakage resulting from production defects. Standard rupture usually originates from abnormal circuit or load conditions, while unanticipated abnormal rupture may secondarily damage connected circuits and equipment. This paper centers its research on abnormal rupture brought on by long-term aging.
3. Defective Electrode Contact
In operating surroundings with high temperature and humidity, electrode metals tend to oxidize easily. This oxidation amplifies contact resistance, overheats electrodes, and ultimately leads to serious contact malfunction. Continuous mechanical vibration can loosen electrode connections, which also generates unstable contact.
Closing Remarks
High-voltage fuses experience performance deterioration and aging after prolonged operation. Nuclear power facilities should carry out periodic inspections on high-voltage fuses, track their aging trends, and develop scientific preventive maintenance plans. These measures can avoid massive system losses caused by the breakdown of high-voltage current-limiting fuses.
As vital protective devices, every instance of fuse rupture demands thorough root cause analysis to confirm whether aging is the triggering factor. If aging is not the cause, technicians need to examine all identical fuses within the system to check for hidden aging risks. If no aging signs are detected, relevant faulty matching parts should be repaired or replaced to eliminate repeated breakage issues.
High-voltage fuses degrade through multiple aging mechanisms. The primary drivers are electromigration and metal vaporization of fuse links, with chemical corrosion acting as a secondary factor. Some aged fuses bear obvious surface damage identifiable via visual check, yet many show no visible exterior flaws. Without damaging the intact fuse, technicians can only rely on precise testing methods—including high-accuracy resistance testing and infrared thermal imaging temperature measurement—to evaluate aging status. Under microscopic observation, aged fuse links display clear microscale damage: partial material loss, surface protrusions, and solidified burrs left after high-temperature cooling.